The Black Wolf

A black wolf is a melanistic colour variant of the grey wolf . Black specimens are recorded among red wolves , but these colour variants are probably extinct. Genetic research from the Stanford University School of Medicine and the University of California, Los Angeles revealed that wolves with black pelts owe their distinctive coloration to a mutation which occurred in domestic dogs, and was carried to wolves through wolf-dog .

Linnaeus gave the black wolves
of Europe the binomial name Canis lycaon, under the assumption that the species was distinct from grey and white coloured wolves. Cuvier and other naturalists largely followed his example. Black wolves were considered rare in France, but common in Southern Europe at the time, with black wolf populations south to the Pyrenees apparently outnumbering other color morphs. They also occurred in the mountains of Friuli (Italy) and around Kotor (Montenegro). Black wolves were also reported to inhabit the Vekvoturian Mountain of Russia. Colonel Smith erroneously believed that the so-called "Rossomak" of the Lenas in Siberia was of the same variety. However, in fact, "Rossomak" in Russian exactly corresponds with the English "wolverine", a mustelid species. Black wolves were considered rare in northern Europe, however, Dr Höggberg, a medical practitioner at Karlstad mentioned five black wolves being killed in the Swedish province of Värmland in 1801.

These wolves were completely black and were bigger than the more common grey variety. Their pelts were considered exotic enough to be sold for 3–4 times the price established for more common colour morphs. Also, the last wolf in Scotland, supposedly killed by MacQueen of Pall à Chrocain is usually narrated as having been black. Cuvier noted that European black wolves differed little in size from other colour morphs, but exceeded them in physical strength. Charles Hamilton Smith wrote that black wolves were generally less aggressive than ordinary kinds, and interbred with dogs more readily.ref<Rare case.In Serbia South-Eastern Europe, Balkan peninsula indicated that on 17.11.2012 a black wolf was killed at Stara mountain.

Black wolves were occasionally reported in Asia. The "Derboun" of the Arabian mountains and southern Syria was a small black wolf which apparently was considered by the Arabs to be more closely related to dogs, as they freely ate its flesh like any other game, unlike with regular wolves which had an unpleasant odour. Black wolves in Tibet are known locally as chanko nagpo, and are considered bolder and more aggressive than the pale coloured variety. Small populations inhabit Ladakh.Although the black wolves of America were originally given the same bionomial name as those in Europe, Anselme Gaëtan Desmarest believed that they were a different species. Historically, the natives of the banks of the Mackenzie River, Saskatchewan River and southern Canada apparently never viewed black wolves as a distinct species. In his 1791 book Travels, William Bartram mentioned seeing black wolves among the few red wolf populations he saw in Florida. He stated that they were "perfectly black", except the females which were described as having a white spot on the breast.

Bartram also described a "black wolf-dog of the Florida Indians" which was identical to the local wolves, save for the fact that it could bark, and could be trusted around horses. The fur of a black wolf was once considered by the natives of New England to be worth over 40 American beaver skins. A chieftain accepting a gift of black wolf fur was seen as an act of reconciliation. The black wolves of the Southern United States were considered a separate species to the northern kind due to differences in colour and morphology, and were named clouded or dusky wolves . The dusky wolves occurred in Missouri Territory, and were intermediate in size between common wolves and coyotes. They apparently produced a foul odour.On January 15, 2009, a black male wolf from "Mollie's Pack" in the Yellowstone National Park's Pelican Valley was weighed in at 143 lbs, making it the largest Yellowstone wolf on record.

In 2008, Dr. Gregory S. Barsh, a professor of genetics and pediatrics at the Stanford University School of Medicine used molecular genetic techniques to analyze DNA sequences from 150 wolves, half of them black, in Yellowstone National Park, which covers parts of Wyoming, Montana and Idaho. It was discovered that a gene mutation responsible for the protein beta-defensin 3, known as the K locus, is responsible for the black coat color in dogs. After finding that the same mutation was responsible for black wolves in North America and the Italian Apennines, he set out to discover the origin of the mutation. Dr. Barsh and his colleagues concluded that the mutation arose in dogs 12,779 to 121,182 years ago, with a preferred date of 46,886 years ago after comparing large sections of wolf, dog and coyote genomes.At the University of California, Los Angeles, Robert K. Wayne, a canine evolutionary biologist, stated that he believed that dogs were the first to have the mutation. He further stated that even if it originally arose in Eurasian wolves, it was passed on to dogs who, soon after their arrival, brought it to the New World and then passed it to wolves and coyotes.Black wolves with recent dog ancestry tend to retain black pigment longer as they age.

As black colored wolves
occur more frequently in forested areas than on the tundra (black coats occur in about 62% of wolves in the forested areas of the Canadian Arctic, compared with about 7% in the icy tundra), melanism was concluded by the researchers to give those wolves an adaptive advantage. The mutation’s purpose has not yet been identified. Dr Barsh ruled out camouflage, as wolves have few natural predators, and there is no evidence that a black coat color leads to any increase in hunting success rates. Dr. Barsh observed that beta-defensin is involved in providing immunity to viral and bacterial skin infections, which might be more common in forested, warmer environments.It has been suggested that the mutation's association with forested habitats means that the prevalence of melanism should increase as forests expand northward.Dark fur is believed to be dominant in wolves.A mating between a black and a gray wolf resultedin ten pups with dark fur out of a total of fourteen.

Black wolves rarely occur in Europe and Asia, where interactions with domestic dogs has been reduced over the past thousand years due to the depletion of wild wolf populations.They have occasionally appeared, as wolf-dog hybrids are known in Russia as "black wolves",and currently, 20–25% of Italy's wolf population is composed of black animals.They are more common in North America; about half of the wolves in the reintroduced wolf population in Wyoming's Yellowstone National Park are black. Like Pyrenees Wolves, Black wolves do not live in France.In southern Canada and Minnesota the black phase is more common than the white, though grey coloured wolves predominate.

Black wolves and coyotes are often the villains of cartoons and children's fairy tales, but it now appears that they inherited their color from a much more warm and fuzzy animal the dog.True, dogs are descended from wolves, but research Friday in the journal Science indicates that black fur was bred into dogs by humans, then inadvertently introduced into the wild species

The trait shows up in the wild primarily in North America, and it was probably brought to the continent about 15,000 years ago when the first immigrants crossed over the Bering land bridge, bringing their dogs with them.The fact that the mutation has stayed in the wild population for so long suggests that it is beneficial in some way.The gene responsible for the color, called beta-defensin, was discovered in 2007 by geneticist Greg Barsh of Stanford University.It belongs to a family of genes thought to be involved in fighting infections.

When the gene appears in its normal form, the animal has a light or yellow-colored coat. But when one copy of the gene is missing three nucleotides, the animal develops a black coat.Studying genes from a large number of wolves, coyotes and dogs, Barsh and his colleagues concluded that the current mutation first appeared in dogs about 50,000 years ago.It may also have appeared in wild animals, then disappeared again, the researchers speculated.They also concluded that the mutation appeared in wolves and coyotes some time after the first humans reached North America.Its almost exclusive appearance in the New World is probably because it was much easier for dogs to mingle with the wild animals here than in Europe, said Barsh's graduate student Tovi Anderson.Black coats occur in about 62% of wolves in the forested areas of the Canadian Arctic, compared with about 7% in the icy tundra. Researchers agree that the coat does not camouflage the animals from predators, but it may help them sneak up on prey.The mutated gene might also provide a better immune defense against infectious agents that occur primarily in the warmer forests, Barsh said.

Black Wolf Mystery Solved

The reason North American wolves have black coats may surprise you; scientists found it’s the result of historical matings between black dogs and gray wolves. Gray wolves have that name because of their color, but in North America many of them have dark or black coats instead of the standard gray.A team of researchers led by Gregory S. Barsh of Stanford University found a genetic mutation producing dark coats appears to have occurred in dogs, and then spread from them to wolves when the species mated. The research, federally funded by the National Science Foundation, is published in the online edition of the journal Science.Researchers discovered that dark-coated wolves are almost exclusive to North America and are common in forested areas where they make up 62 percent of the wolf population, compared with 7 percent in open tundra.

But wildlife biologists don’t think wolves rely much on camouflage, Barsh said. "It’s possible there is something else going on here.""It’s sort of intuitively appealing, when you see animals that sort of blend in with their environment, to say … that explains natural selection, that somehow they are better camouflaged either as predator or prey," said Barsh. However, he said wolves don’t have a lot of predators, and there’s no evidence a black coat color leads to any increase in a wolf’s ability to capture its prey.The scientists used molecular genetic techniques to analyze DNA sequences from 150 wolves, about half of them black, in Yellowstone National Park, which covers parts of Wyoming, Montana and Idaho. Researchers found that a mutated gene in dogs, known as the K locus, is responsible for black coat color.The same protein responsible for coat color is associated with fighting inflammation and infection in humans.Thus, it "might give black animals an advantage that is distinct from its effect on pigmentation," Barsh said.Researcher Tovi Anderson said humans have cultivated the mutation for black coats in the domestic dog for thousands of years.

"Now we see that it not only entered the wild population, but also is benefiting them," she said.Genetic tests show the mutation was introduced into wolves by dogs sometime in the last 10,000 to 15,000 years, Anderson said. "We usually think of domestication as something that is carried out to benefit humans," Barsh said. "So we were really surprised to find that domestic animals can serve as a genetic reservoir that can benefit the natural populations from which they were derived.""Although it happened by accident, black wolves are the first example of wolves being genetically engineered by people," added co-author Marco Musiani of the University of Calgary in Canada. "It is somewhat ironic that a trait that was created by humans may now prove to be beneficial for wolves as they deal with human-caused changes to their habitat."

The effect was more than just cosmetic: the resulting black wolves, which are found nearly exclusively in North America, seem to have a selective advantage over lighter-colored wolves in forested areas. It's a rare instance of domestic animals in this case, probably the dogs of the earliest Native Americans contributing to the genetic variability of their wild counterparts in a way that affects both the recipients' appearance and survival."We usually think of domestication as something that is carried out to benefit humans," said genetics professor Greg Barsh, MD, PhD. "So we were really surprised to find that domestic animals can serve as a genetic reservoir that can benefit the natural populations from which they were derived. It's also fascinating to think that a portion of the first Native American dogs, which are now extinct, may live on in wolves." Canine geneticists generally agree that North American dogs today are all descended from European dogs.

Anderson and her collaborators compared DNA collected from 41 black, white and gray wolves in the Canadian Arctic and 224 black and gray wolves in Yellowstone National Park with that of domestic dogs and gray and black coyotes. Their intention was to build on previous work in the Barsh lab that identified a mechanism controlling pigmentation in dogs that differs from most other mammals.

"We expected this to be a short research project to confirm that wolves and dogs shared the same genetic pathway that determines black coat color," said Anderson. "But the story got much more interesting when we expanded our research and began asking about the origin of the mutation in wolves."

Dark-coated wolves are significantly more prevalent in forested areas of the Canadian Arctic than they are in the icy tundra (62% vs. 7% of the total population, respectively). Biologists have long suspected that something about having black fur is particularly advantageous for the woodland wolves, but they weren't sure what. Because black wolves gray with age, it seems that the root cause might be deeper than just coat color.

Barsh's laboratory, which has spent years studying genes affecting coat color and other biological pathways in mammals, discovered in 2007 that the gene responsible for black fur in dogs, called beta-defensin, belongs to a family of genes previously believed to be involved in fighting infection. One version of the gene produces light or yellow-colored dogs and wolves; a mutant version missing three nucleotides produces black animals.

"Wildlife biologists don't really think that wolves rely much on camouflage to protect themselves or to increase their hunting success," said Barsh. "It's possible there is something else going on here. For example, the protein responsible for the coat color difference has been implicated, in humans, in inflammation and infection, and therefore might give black animals an advantage that is distinct from its effect on pigmentation."

Although the "why" of this selective advantage remains a mystery, the "how" is becoming more clear. Anderson's study confirmed that the black-coat gene shows evidence of positive selection in forest wolves. She also showed that the gene is dominant, meaning that an animal with only one copy of the gene would still have a black coat. Ten of fourteen pups of a mating between a black wolf and a gray wolf carried the gene and were black.

She and her collaborators used a variety of genetic tests to determine that the mutation was likely introduced into wolves by dogs sometime in the last 10,000 to 15,000 years, about the same time the first Americans were migrating across the Bering land bridge. These humans were probably accompanied by dogs, some of which carried the black-coat mutation estimated to have arisen about 50,000 years ago. The rest, as they say, was history.

"It may have been easier for dogs to interact with wolves in North America than in Europe," said Anderson. "There was probably a higher concentration of wolves, and the dogs, like the humans, were more migratory."

Unfortunately, it's not yet possible to tell whether there were any black wolves prior to the domestication of dogs. It may be that the mutation arose in the wolf population prior to the domestication of the dog somewhere between 15,000 and 40,000 years ago and then died out in the wild. Alternatively, it may have made its first appearance in a domestic dog and never entered the wild until the Native Americans migrated from Europe. Regardless, it's the seemingly beneficial aspect of the mutation coupled with its origin that has the researchers excited.

"This is a mutation that had been cultivated by humans in the form of the domestic dog for thousands of years," said Anderson. "Now we see that it not only entered the wild population, but also is benefiting them." The researchers speculate that the loss of the wolves' tundra habitat may encourage the spread of the black-coat gene even further. They're interested in finding out exactly how the mutation works to help forest wolves.

"It is somewhat ironic that a trait that was created by humans may now prove to be beneficial for wolves as they deal with human-caused changes to their habitat," said Marco Musiani, an internationally-recognized expert on wolves and a professor in the University of Calgary's Faculty of Environmental Design, who was one of the researchers.Barsh and Anderson's Stanford collaborators include Hua Tang, PhD, assistant professor of genetics, and Sophie Candille, PhD, postdoctoral fellow in the Tang lab. The research was funded by the National Institutes of Health, the National Science Foundation and the Swedish Research Council.

The research underscores the idea that evolution may involve other instances in which traits are passed in unexpected directions. "We now know that dogs have been the caretakers of a genetic legacy that may be very beneficial to wolves," said Barsh. "It should lead us to think more broadly as to how this might apply to other animals and plants."With tundra habitat expected to decline in coming years due to northern expansion of boreal forests related to global warming, the researchers note that black coloring may also help gray wolves adapt to their changing environment.